GB2065572A

GB2065572A - Vehicle wheel rims

Info

Publication number: GB2065572A
Application number: GB8039363A
Authority: GB
Original assignee: Bridgestone Corp
Current assignee: Bridgestone Corp
Priority date: 1979-12-12
Filing date: 1980-12-09
Publication date: 1981-07-01
Also published as: DE3046514A1; FR2471868A1; JPS5687902U; JPS5819042Y2; FR2471868B1; DE3046514C2

Abstract

A wheel rim comprises a pair of flange parts (1a, 1b), a pair of tyre bead seat parts (2a, 2b), a well part (4), and a straight part (3) for securement to a disc member (5), the thicknesses of the bead seat part (2a) located at the opposite side of the well part from the disc member, the side wall of the well part adjoining part (2a) and the base of the well part being greater than the thicknesses of the other remaining parts of the rim. <IMAGE>

Description

SPECIFICATION Rim members in wheel assemblies for vehicle tires This invention relates to rim members in wheel assemblies for vehicle tires.

1 5 deg full drop center rim members used in wheel assemblies for trucks and buses are usually manufactured by a method wherein a steel plate is rolled into a cylindrical form and then subjected to a roll molding after butt welding, or by a method wherein a steel plate previously shaped into a form corresponding to the section of the rim is rolled into a cylindrical form and then welded. In either case, however, the conventional rim members of this type have various drawbacks as follows. That is, the thickness of the steel plate is locally changed in its widthwise direction, but such a change of the thickness is not appropriately related to the distribution of stress acting on the rim member, so that portions of the rim subjected to a large stress are apt to cause fatigue failure as compared with the remaining portions of the rim in use.Conversely, the surplus thickness of portions subjected to a smaller stress brings about an increase of rim weight and further an increase of rim cost.

The present invention provides a rim member in a wheel assembly for vehicle tires, comprising a pair of flange parts, a pair of bead seat parts, a well part, a straight part, and a disc member bonded to the straight part, wherein the thicknesses of the well part and the bead seat part located at the opposite side of the well part from the disc member are greater than thicknesses of the other remaining parts of the rim member.

The invention is based on the knowledge that the magnitude of stress acting on a rim member is different at parts of the rim member in the widthwise direction, and advantageously solves the above mentioned drawbacks by increasing the thickness of those parts which are particularly subjected to a large stress as compared with the remaining parts so as to substantially equalize the stress acting on each part of the rim member in the widthwise direction thereof.

The invention will be further described, by way of example only, with reference to the accompanying drawings, wherein: Figure 1 is a diagrammatic view illustrating a section of a conventional rim member and the stress distribution thereof; and Figure 2 is a diagrammatic sectional view of an embodiment of a rim member according to the present invention.

In Fig. 1 is shown a section of a conventional 1 5 deg full drop center rim member for use in trucks and buses and the stress distribution of this rim member in its widthwise direction. This rim member comprises flange parts 1 a, 1 b, bead seat parts 2a, 2b each inclined at an angle of 1 5, with respect to the horizontal plane so as to elevate the flange parts, a straight part 3 adjacent the inside of the bead seat part 2b, a well part 4 located between the straight part 3 and the bead seat part 2a, and a disc member 5 bonded to the straight part 3 at its inner peripheral side by for example welding.

In the above-described conventional rim member having a uniform thickness, the stress acting on each part of the rim member in its widthwise direction was measured by a strain gauge attached to each part of the rim member under such conditions that the air pressure was 10 kg/cm2, the load was 3000 kg and the side force was 500 kg. As a result, it has been confirmed that the bending stress acts on the well part 4 of the rim member, while the tensile stress acts on the other remaining parts thereof, and the magnitude of the stress acting on these parts is expressed by a shaded area as shown in Fig. 1.When concretely comparing these measured results with numerical values, the stress acting on the well part 4 is a4 = 2.5-3.0 and the stress acting on the bead seat part 2a is a2a = 1.8-2.0, which are considerably larger than a, = 1.5 being a mean value of stresses acting on the other remaining parts of the rim member.

Therefore, the service life of the conventional rim member having a uniform thickness is determined by fatigue failure caused in any part of the rim member.

The present inventors have made studies with respect to the relationship between the thickness of the rim member and the stress acting thereon, and as a result the present invention has been accomplished. That is, assuming that the thickness of a certain part of the rim member is t1, the stress acting on this part is at and the moment acting thereon is constant, the thickness t2 when the stress changes into a2 is expressed by the following equation (1) from a,t2, = a2t22 in case of bending stress or equation (2) from a,t, = a2t2 in case of tensile stress::

t2 = a, /a2t1 (2) Now, when the thickness of the rim member is uniform with a mean thickness t,,,, the thickness t4 of the well part is t4 = tm In order to reduce the stress a4 acting on the well part to a stress a,, with constant moment. the thickness t'4 becomes

as calculated from the equation (1). Similarly, in order to reduce the stress acting on the bead seat part to am, the thickness t'2a becomes

as calculated from the equation (2).

That is, according to the invention, a rim member having substantially a uniform stress distribution can be obtained by making the thickness of the well part 4 1.3-1.4 times the thickness of the remaining part and also the thickness of the bead seat part 2a 1.2-1.3 times the thickness of the remaining part as shown in Fig. 2.

Although the invention is described with respective to the above illustrated embodiment, it is, of course, applicable to rim members other than 1 5 deg full drop center rim members.

According to the invention, the stress acting on the rim member is substantially equalized at any part of the rim member in the widthwise direction, so that local fatigue failure is prevented to improve the durability of the rim member. Furthermore, the rim weight and cost can be reduced by reducing the thickness of unnecessary parts of the rim member.

Claims

1. A rim member in a wheel assembly for vehicle tires, comprising a pair of flange parts, a pair of bead seat parts, a well part, a straight part, and a disc member bonded to the straight part, wherein the thicknesses of the well part and the bead seat part located at the opposite side of the well part from the disc member are greater than thicknesses of the other remaining parts of the rim member.

2. A rim member as claimed in claim 1, wherein the thicknesses of the well part and the said bead seat part located opposite from the disc member are respectively 1.3-1.4 and 1.2-1.3 times the thickness of the remaining parts of the rim member.

3. A rim member as claimed in claim 1 or 2, which is a 1 5 deg full drop center rim member.

4. A rim member according to claim 1, substantially as herein described with reference to, and as shown in, Fig. 2 of the accompanying drawings.